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By an individual unacquainted with the manner in 

 which these concretions have been produced, particularly 

 those that assume the rounded form, so great is their re- 

 semblance, they might very easily be mistaken for water- 

 worn fragments of some firmly indurated rock ; and had 

 the material of which they have been constructed been 

 somewhat more copious, there can be but little doubt but 

 that a solid stratum of silicious limestone would have been 

 the result, occupying a position in conformity with the 

 strata of this heavy mass of ductile clay. 



These clay-stones, as they are most commonly called, or 

 calcareous concretions, have frequently been the cause of 

 some considerable speculation among geologists, in en- 

 deavoring to account for their production. The manner 

 in which they have been formed is distinctly perceptible 

 everywhere, among the various and extensive diggings 

 which have thrown them open to the light of day. The 

 delicate fibres of the roots of the different trees of the 

 forest that at one time completely covered the surface of 

 the soil, have, in innumerable instances, penetrated to a 

 very considerable distance beneath. It was along these 

 roots that the moisture from the surface, highly charged 

 with carbonic acid gas, readily found its way, collecting 

 the lime and other necessary ingredients in its descent, 

 until its arrival at one of these seams of sand ; here a de- 

 position commenced, and the particles gradually arranged 

 themselves in a concretionary form around a nucleus of 

 ligneous fibre. 



Whenever these concretions have been examined in a 

 perfect state, this nucleus, or remnants of it, has invariably 

 been found, exhibiting no other change in its appearance 

 than that of a brownish stain given to it by the oxide of 

 iron. Sometimes two or more of them may be seen united 

 together ; at others, where the deposition seems to have 

 been far more copious, the liquid masi appears to have 

 spread out to some considerable extent, giving origin to 



